The use of mechanical circulatory support has grown in the adult population from early postcardiotomy support, to bridge-to-transplant support, to destination therapy for congestive heart failure. Survival to transplant, survival post-transplant, and survival in destination therapy applications relative to optimum medical therapy, have demonstrated the success of this technology in adult heart failure patients. However, application of mechanical circulatory support in the pediatric population has been limited. It is estimated that the number of pediatric patients requiring support is much smaller than the adult population. The potential market for pediatric circulatory support devices is subsequently smaller. In addition, the design of small blood pumps is challenging due to the increasing importance of fluid viscous effects as pump dimensions are reduced, which may lead to thrombus formation. We propose the development of a pulsatile blood pump based on the design of the successful adult-sized Pierce-Donachy ventricular assist device (VAD). This pump design has been used in over 2000 patients worldwide as the Thoratec V AD. This approach is advantageous in pediatric applications because the system provides pulsatile flow, is relatively non-thrombogenic, is durable, and may be used for uni-ventricular or bi-ventricular support. Two pediatric pump sizes will be developed;a 10 ml stroke volume pump for infants, and a 25 ml stroke volume pump for children. The adult pump has a 65 ml stroke volume. Previous work at Penn State with a 10 ml design included a series of 30 animal studies and in vitro measurements of the flow field in the pump using Particle Image Velocimetry (PN) and Laser Doppler Velocimetry (LDV). A novel pneumatic portable driver will be developed. The driver is based on actuator technology developed by Penn State for electrically-powered implantable blood pumps. The driver design is unique in this application due to its ability to control the shape of the applied pressure waveforms, and the potential for excellent durability, portability, and low noise. Penn State has gained significant expertise in the design, development, clinical use, and technology transfer of circulatory support systems. In addition to the Pierce-Donachy pneumatic VAD, the fully implantable VAD known as the Arrow Lionheart was developed at Penn State and is currently in clinical trials. The Penn State Total Artificial Heart (TAH) was designed under NHLBI contract support and is currently under further development. This multidisciplinary expertise, along with the continuing improvements in biomaterials, surface analysis, flow field imaging, and electronics, will be applied to developing a clinically-ready pediatric assist system.